Free water clearance of -1.3 ml/min signifies

In the physiology of the kidney, free water clearance (CH2O) is the volume of blood plasma that is cleared of solute-free water per unit time. If an individual is producing urine more dilute than the plasma, there is a positive value for free water clearance, meaning pure water is lost in the urine in addition to a theoretical isoosmotic filtrate. If the urine is more concentrated than the plasma, then free water is being extracted from the urine, giving a negative value for free water clearance.Ref: Ganong&;s review of medical physiology; 23rd edition; page no; 657